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ARNOLD HOERMANN, OF NEW YORK, N. Y.

Lettere .Patent No. 82,118, dated September 15, 1868; antedatedSeptemter 4, 1868.

IMPROVEMENT IN SGEEW-GUTTING DIESc tite rtemle marsh mit there tettlrs@sont ont making not nf ilge time.

To ALL wnoM'Ifr MAY ooNoEnN:

Be it known that I, ARNOLD HOERMANN, of the city and county of New York,and State of New York, have invented certain new andl usefulImprovements in Dies for Cutting Screws; land I do hereby declare thatthe following is a full-and exact description thereof.

i I will first describe what I consider the best means of carrying outmy invention, and will afterwards dosignate the points which'I believeto he new.

The accompanying drawings form a part of this specification.

Figure 1 is an edge view, vand Figure 2 a face view of one form of myimprovement.

Figure ,3 is an edge view.

. Figure 4, a face view of another form, and

Figure 5 is a face view of another form. Figure@ is a. magnifiedcross-section of a part of a screw, cut according to the ordinary plan,showing the metal partly forced up, to form the thread.

Figure 'i' is a corresponding cross-section of a part of a screw, cutaccording to my improved plan, that is to say, with the use of myinvention, showing the-metal out more clearly away, and threadconsequently being more sound. l k e Figures 8 to 17, inclusive,indicate the means which I propose to employ in manufacturing myimproved dies. They represent the dies'in the act of being milled on theface which receives the material to be cut. The several iiguresrepresent 'mills in different positions and in different forms forfinishing the face of the die properly, according to this invention.

Figure 18 is an edge view of another form of my invention.

Figure 19 is a face view of the same, and

Figure 20 is an edge view of the oppositeedge of the same.

Figure 20 is a sketch of another form of the inclined position of thecavity, which is the principal peculiarity shown in g. V20. In this fig.20l the inclination is in a direction opposite to that shown in iig. 20.I prefer the position shown in iig. 20*.V l, v

Similar letters of reference indicate like parts in all the figureswhere they occur.

Referring to figs. 1 and 2, A is a solid bur of -hardened steel; B C D,dto., are holes, drilled perpendicularly therein, and tapped in. theordinary manner, so as to form a'clear and well-defined internal thread,adapted to he subsequently used for cutting screws. The holes m'ay beall of the same size, or they may he of different sizes, adapted to cutdiferent screws; or there may he hut one hole in the entire piece ofmetal, leaving the remainder of the metal to serve merely as handles forholding it; or the metal may be smaller, and confined by any suitabletool or machine for holding it. I have, for convenience, represented anumber of holes, of different sizes and threads, produced inthe samepiece of steel.

The surface, at the upper edge of each hole, is not a planeperpendicular to the hole. In some, the surfaces are simply oblique; inothers, they are portions hollowed in various curves; and in others,they are chamforcd and shouldered in various ways, as shown in figs. 1and 2. The effectin every case is to present to the blank two or moreofthe cutting-'threads in full sectional relief, which trace the threadon the blank by cutting out, and at the same time removing, the portionof metal so out out, in the manncr'of the cutting-tool ci' an ordinaryplaner, cutting cleanly into the material of the iron, brass, or othermetal on which the screw is to be produced.

It will of course be understood that the manipulation for cutting thescrew by my improved die is, in general terms, thc same as in cuttingwith other dies. A plain cylindrical bolt or wire is tapered slightly atone end, and introduced at the upper end of the hole, and is turnedaround therein; or the cylindrical rod being held stationary, the die Ais turned around upon it.

As solid dies havo been heretofore constructed, the face or edgesurrounding the hole has been plane, and at right angles to the axis ofthe h ole; consequently the entering end of the hole forms but one longtooth all around the'hole, which has to force itself into the blankwithout cutting out the metal. Ami if there are formed teeth in fullsectional relief, by making one or more notches or openings, the longtooth or thread opposite these full sectional teeth has to force itselfalso into the blank before it comes to those teeth; consequently theycannot cutout the thread; they only remove the metal in fine powder, andleave the greater part forced up. In my improved dies this long tooth istaken away, by forming the surface in the aforesaid manner; consequentlythe blank is presented in full to the cutting-tooth or edge, which canby these means cnt out the metal cleanly, as a chisel in a planerorlathe, as plainly shown in red.

I have tested my invention on various metals, Mydiescommencc with cleancuts, so that, after cutting, the screw is of the same diameter andlength as the wire or bolt was befere, while the ordinary dies make lessperfect threads, and produce them partly by cutting, and partly bycrushing and destroying or squeezing p the metal, so that, aftercutting, the screw is always -larger in diameter and longer than thewire or bolt was before the cutting. i Y* Referring to figs. 3, 4, and5, we find two series of holes, each near the edge of the plate, andeach opening quite to the edge, by a small aperture, specially provided.In this construction the opening provides a series of corners or teeth,opposite which the threads are taken away, so as to allow these cornersto cut in the before-described manner. i

It is common in dies to Agroove or spline along one side of the hole,and in some instances this has been done at two or more points. Suchsplining increases the number of corners which are presented in cuttingthe thread; but I have demonstrated' by experiment that the additionalcorners presented in my improved diesare far more effective. Increasingthe number of corners by the old method, increased the efficiency of thedie, but the metal is removed in the form of ne dust, and the thread isproduced largely by compressing and destroying the' metal. The outeredge of the threads so produced is soft and weak. The outer edge of mythreads is as irm as any portion of the metal. ,I ascribe thisdifference mainly to a slight bending or'springing of the bar or wire.There is a strain on the wire in entering my die, tending to bend itover to one side. I believe that my metal yields, to la limited extent,to this strain, and that the diierence in the manner in which the metalis presented is suiicient, for this reason, to account for the change inthe eifect. t

My dies cut, in practice, clean shavings of iron or brass, havingcoherent qualities, and curling up .as they are removed, while theordinary dies, corresponding thereto, remove the material in the form ofiinepowder.

The ordinary dies crush up the metal so as to form threads which are,complete in their appearance, but

which are oftentimes not sound in their internal structure. `Fig. 6shows, in an enlarged section, the bad internal condition of the metalof the screw out by ordinary dies. Fig. 7 showsI the perfect conditionof the screws cnt by my dies. i

Fig. y17 shows a tapering mill,vused to remove `a portion of the rstthreads or teeth before the die is hardened. It leaves the firsttoothigreatly shortened, and the'next one slightly shortened, so thatthe first tooth cuts only one-third of the thread, the second anotherthird, and the'third completes it.

Referring to figs. 18, 19, and 20, only fourl holes, B, C, D, and E, arerepresented. The holes B and E are formed in the .solid metal of theplate, which ig milled out by the means indicated in gs. 8 to 13, and intig. 17, so as to produce the peculiarities of my invention. The holes Cand D, however, have additional novel features.

On introducing the bolt to my improved dies, it is liable to spring overto one side, as above described, to too great a distance. To avoid this,I apply, on the entering-face of my improved screw-plate, when intendedfor large screws, say quarter-inch and larger, guides formed andarranged as represented by M. These guides are secured to`the main bodyof the screw-plate by screws m, as represented, so that they may heremoved at pleasure, to allow the repairing or sharpening of the cuttingportions of the dies. The holes in this guide M are but.little largerthan the bolt or blank screw which is to be cut. They receive it freely,and support it firmly against becoming deflected to too great an extent.-This guide is important mainly in entering the screw, or firstcommencing to cut the screw-thread on the end of the bolt. After thework has been fairly commenced the guide is of far less importance. l d

Each of these holes', C and D, communicates by a slot with the edge ofthe die-platc, that connecting'die. D with the edge of the plate being,at the entering-face of the die, coincident with the centre of said dieor hole, but thence running in an oblique direction across the edge ofthe plate, while that connecting-die C with the edge of the plate,instead of being coincident with the centre of the die or hole, isplaced in advance of said centre, and is directed through the die-plate,perpendicularly to its surface, and not obliquely, as in the lformercase.

The holo C' has another peculiarity. The steel which forms thecutting-angle, and which, consequently, performs nearly or quite all thelabor of cutting the screw-thread, is in a separate piece, as indicatedby N. This piece is of steel, hardened to the proper degree, and may beremoved and exchanged as often as desired, in order to maintain a highdegree of perfection in these cutting-edges. It may readily be groundon'a grindstone, and this operation may be repeated until the openingC', which communicates between the hole G and the edge of thevscrew-plate, becomes inconveniently wide. This separate-piece of steel,N, is secured to the main body of the screw-plate by screws n, asrepresented. y

I do not claim in this patent any of the special constructionsrepresented by igs. 6 to I6 inclusive; but

What I do claim as new in dies for cutting screws,'and desire to secureby Letters Patent, is as follows:

1. I claim a screw-cutting die, having a recessed surface, so as topresent two or more cutting-threads in full sectional relief, asdescribed and shown.

2. I claim the die C, having a recessed surface, so as to present two ormore cutting-threads in full sectional relief, combined ywith the slotCf, set in advance of the entre of the die, all as vset; forth.

3. I claim the guide M, in combination with adie having portions of oneor more threads entirely removed from the entering-face thereof, theseveral parts being constructed and arranged substantially as and forthe .purpose herein sei'. forth. A. HOERMANN.

Witnesses:

C. C. LIVINGS, l WM. C. DEY.

